The invention relates to a group of several camshafts that are each in driven connection with a camshaft adjuster.
Camshaft adjusters can be roughly classified, in principle, as follows:
A. Phase adjusters with a control element, that is, a functional unit that engages in the flow of mass or energy and that is constructed, for example, hydraulically, electrically, or mechanically and that rotates with gear elements of the camshaft adjuster.
B. Phase adjusters with a separate controller, that is, a functional unit in which the control parameter required for controlling the control element is formed from controller output parameters and with a separate control element. Here, there are the following configurations:
a. Phase adjusters with a co-rotating actuator and a co-rotating control element, for example, a speed-increasing gearbox whose adjustment shaft can be preset by a co-rotating hydraulic motor or centrifugal force motor and can be reset by a spring.
b. Phase adjusters with a co-rotating control element and a stationary, motor-fixed actuator, for example, an electric motor or an electric or mechanical brake, see also DE 100 38 354 A1, DE 102 06 034 A1, EP 1 043 482 B1.
c. Phase adjusters with a direction-dependent combination of solutions according to a. and b., for example, a motor-fixed brake in which a part of the brake power is used for an advanced adjustment, in order to tension a spring that allows readjustment after the brake is deactivated, see also DE 102 24 446 A1, WO 03-098010, US 2003 0226534, DE 103 17 607 A1.
In systems according to B.a. to B.c., actuators and control elements are connected to each other by an adjustment shaft. The connection can be switchable or non-switchable, detachable or non-detachable, with or without play, and elastic or stiff. Independent of the configuration, the adjustment energy can be realized in the form of a provision of drive power and/or brake power as well as the use of stray power of the shaft system (e.g., friction) and/or inertia and/or centrifugal forces. Braking, advantageously in the “retarded” adjustment direction can also be realized under complete use or joint use of the friction power of the camshaft. A camshaft adjuster can be equipped with or without mechanical limiting of the adjustment region. One-stage or multiple-stage triple-shaft gearboxes and/or multiple linkages or coupling gearboxes are used as gearboxes in a camshaft adjuster, for example, in a configuration as a swashplate gearbox, eccentric gearbox, planetary gearbox, harmonic drive, cam-disk gearbox, multiple linkage or coupling gearbox, or combinations of the individual configurations for a multiple-stage construction.
While conventional, hydraulically activated camshaft adjusters or camshaft adjusters in a configuration with vane cells, pivot vanes, or segmented vanes have the advantage that
the hydraulic medium for control can be fed at any position in the camshaft adjuster,
the hydraulic medium can be forwarded in the camshaft adjuster via suitable flow channels,
the hydraulic medium—if required—can be redirected, and
suitable devices for controlling the hydraulic pressure can also have a decentralized arrangement from the camshaft adjuster,
in conventional camshaft adjusters in which the control movement is generated by an electric motor and a super-position gearbox, triple shaft gearbox, or planetary gearbox (below, super-position gearbox), see, for example, DE 41 10 195 A1, the electric motor is typically arranged flush to the longitudinal axis of the camshaft and the super-position gearbox in front of the super-position gearbox. The control assemblies responsible for generating the control movement of a camshaft adjuster can be used as a brake and also as a motor. The use of a hydraulic valve for generating the control movement in which a magnet must be arranged for activation in the centered position is also possible.
For a rotationally fixed connection between a connection element of the camshaft adjuster and the camshaft, e.g.,
a central screw can be used that extends through a passage borehole of the connection element and is screwed on the front end into an axially oriented thread of the camshaft, so that the connection element is tightened with the camshaft, see, e.g., DE 100 38 354 C2, DE 102 48 355 A1, EP 0 356 162 B1,
an end-side flange of the camshaft can be screwed eccentrically with a counter flange of the connection element, see, e.g., DE 44 15 524, DE 196 11 365 C2,
a multifunctional connection element can be screwed directly into a front-side borehole of the camshaft, cf. DE 198 48 706 A1.